列出空安全问题
lists in null safety issue
我收到一个关于模型列表的空安全问题
The default 'List' constructor isn't available when null safety is
enabled.Try using a list literal, 'List.filled' or 'List.generate'.
这是代码：
var productList = List<Product>().obs;
模态代码：
import 'dart:convert';
List<Product> welcomeFromJson(String str) => List<Product>.from(json.decode(str).map((x) => Product.fromJson(x)));
String welcomeToJson(List<Product> data) => json.encode(List<dynamic>.from(data.map((x) => x.toJson())));
class Product {
Product({
required this.id,
required this.name,
required this.slug,
required this.permalink,
required this.dateCreated,
required this.dateCreatedGmt,
required this.dateModified,
required this.dateModifiedGmt,
required this.type,
required this.status,
required this.featured,
required this.catalogVisibility,
required this.description,
required this.shortDescription,
required this.sku,
required this.price,
required this.regularPrice,
required this.salePrice,
this.dateOnSaleFrom,
this.dateOnSaleFromGmt,
this.dateOnSaleTo,
this.dateOnSaleToGmt,
required this.onSale,
required this.purchasable,
required this.totalSales,
required this.virtual,
required this.downloadable,
required this.downloads,
required this.downloadLimit,
required this.downloadExpiry,
required this.externalUrl,
required this.buttonText,
required this.taxStatus,
required this.taxClass,
required this.manageStock,
required this.stockQuantity,
required this.backorders,
required this.backordersAllowed,
required this.backordered,
required this.lowStockAmount,
required this.soldIndividually,
required this.weight,
required this.dimensions,
required this.shippingRequired,
required this.shippingTaxable,
required this.shippingClass,
required this.shippingClassId,
required this.reviewsAllowed,
required this.averageRating,
required this.ratingCount,
required this.upsellIds,
required this.crossSellIds,
required this.parentId,
required this.purchaseNote,
required this.categories,
required this.tags,
required this.images,
required this.attributes,
required this.defaultAttributes,
required this.variations,
required this.groupedProducts,
required this.menuOrder,
required this.priceHtml,
required this.relatedIds,
required this.metaData,
required this.stockStatus,
required this.links,
});
int id;
String name;
String slug;
String permalink;
DateTime dateCreated;
DateTime dateCreatedGmt;
DateTime dateModified;
DateTime dateModifiedGmt;
String type;
String status;
bool featured;
String catalogVisibility;
String description;
String shortDescription;
String sku;
String price;
String regularPrice;
String salePrice;
dynamic dateOnSaleFrom;
dynamic dateOnSaleFromGmt;
dynamic dateOnSaleTo;
dynamic dateOnSaleToGmt;
bool onSale;
bool purchasable;
int totalSales;
bool virtual;
bool downloadable;
List<dynamic> downloads;
int downloadLimit;
int downloadExpiry;
String externalUrl;
String buttonText;
String taxStatus;
String taxClass;
bool manageStock;
dynamic stockQuantity;
String backorders;
bool backordersAllowed;
bool backordered;
dynamic lowStockAmount;
bool soldIndividually;
String weight;
Dimensions dimensions;
bool shippingRequired;
bool shippingTaxable;
String shippingClass;
int shippingClassId;
bool reviewsAllowed;
String averageRating;
int ratingCount;
List<dynamic> upsellIds;
List<dynamic> crossSellIds;
int parentId;
String purchaseNote;
List<Category> categories;
List<dynamic> tags;
List<Image> images;
List<dynamic> attributes;
List<dynamic> defaultAttributes;
List<dynamic> variations;
List<dynamic> groupedProducts;
int menuOrder;
String priceHtml;
List<int> relatedIds;
List<dynamic> metaData;
String stockStatus;
Links links;
factory Product.fromJson(Map<String, dynamic> json) => Product(
id: json["id"],
name: json["name"],
slug: json["slug"],
permalink: json["permalink"],
dateCreated: DateTime.parse(json["date_created"]),
dateCreatedGmt: DateTime.parse(json["date_created_gmt"]),
dateModified: DateTime.parse(json["date_modified"]),
dateModifiedGmt: DateTime.parse(json["date_modified_gmt"]),
type: json["type"],
status: json["status"],
featured: json["featured"],
catalogVisibility: json["catalog_visibility"],
description: json["description"],
shortDescription: json["short_description"],
sku: json["sku"],
price: json["price"],
regularPrice: json["regular_price"],
salePrice: json["sale_price"],
dateOnSaleFrom: json["date_on_sale_from"],
dateOnSaleFromGmt: json["date_on_sale_from_gmt"],
dateOnSaleTo: json["date_on_sale_to"],
dateOnSaleToGmt: json["date_on_sale_to_gmt"],
onSale: json["on_sale"],
purchasable: json["purchasable"],
totalSales: json["total_sales"],
virtual: json["virtual"],
downloadable: json["downloadable"],
downloads: List<dynamic>.from(json["downloads"].map((x) => x)),
downloadLimit: json["download_limit"],
downloadExpiry: json["download_expiry"],
externalUrl: json["external_url"],
buttonText: json["button_text"],
taxStatus: json["tax_status"],
taxClass: json["tax_class"],
manageStock: json["manage_stock"],
stockQuantity: json["stock_quantity"],
backorders: json["backorders"],
backordersAllowed: json["backorders_allowed"],
backordered: json["backordered"],
lowStockAmount: json["low_stock_amount"],
soldIndividually: json["sold_individually"],
weight: json["weight"],
dimensions: Dimensions.fromJson(json["dimensions"]),
shippingRequired: json["shipping_required"],
shippingTaxable: json["shipping_taxable"],
shippingClass: json["shipping_class"],
shippingClassId: json["shipping_class_id"],
reviewsAllowed: json["reviews_allowed"],
averageRating: json["average_rating"],
ratingCount: json["rating_count"],
upsellIds: List<dynamic>.from(json["upsell_ids"].map((x) => x)),
crossSellIds: List<dynamic>.from(json["cross_sell_ids"].map((x) => x)),
parentId: json["parent_id"],
purchaseNote: json["purchase_note"],
categories: List<Category>.from(json["categories"].map((x) => Category.fromJson(x))),
tags: List<dynamic>.from(json["tags"].map((x) => x)),
images: List<Image>.from(json["images"].map((x) => Image.fromJson(x))),
attributes: List<dynamic>.from(json["attributes"].map((x) => x)),
defaultAttributes: List<dynamic>.from(json["default_attributes"].map((x) => x)),
variations: List<dynamic>.from(json["variations"].map((x) => x)),
groupedProducts: List<dynamic>.from(json["grouped_products"].map((x) => x)),
menuOrder: json["menu_order"],
priceHtml: json["price_html"],
relatedIds: List<int>.from(json["related_ids"].map((x) => x)),
metaData: List<dynamic>.from(json["meta_data"].map((x) => x)),
stockStatus: json["stock_status"],
links: Links.fromJson(json["_links"]),
);
Map<String, dynamic> toJson() => {
"id": id,
"name": name,
"slug": slug,
"permalink": permalink,
"date_created": dateCreated.toIso8601String(),
"date_created_gmt": dateCreatedGmt.toIso8601String(),
"date_modified": dateModified.toIso8601String(),
"date_modified_gmt": dateModifiedGmt.toIso8601String(),
"type": type,
"status": status,
"featured": featured,
"catalog_visibility": catalogVisibility,
"description": description,
"short_description": shortDescription,
"sku": sku,
"price": price,
"regular_price": regularPrice,
"sale_price": salePrice,
"date_on_sale_from": dateOnSaleFrom,
"date_on_sale_from_gmt": dateOnSaleFromGmt,
"date_on_sale_to": dateOnSaleTo,
"date_on_sale_to_gmt": dateOnSaleToGmt,
"on_sale": onSale,
"purchasable": purchasable,
"total_sales": totalSales,
"virtual": virtual,
"downloadable": downloadable,
"downloads": List<dynamic>.from(downloads.map((x) => x)),
"download_limit": downloadLimit,
"download_expiry": downloadExpiry,
"external_url": externalUrl,
"button_text": buttonText,
"tax_status": taxStatus,
"tax_class": taxClass,
"manage_stock": manageStock,
"stock_quantity": stockQuantity,
"backorders": backorders,
"backorders_allowed": backordersAllowed,
"backordered": backordered,
"low_stock_amount": lowStockAmount,
"sold_individually": soldIndividually,
"weight": weight,
"dimensions": dimensions.toJson(),
"shipping_required": shippingRequired,
"shipping_taxable": shippingTaxable,
"shipping_class": shippingClass,
"shipping_class_id": shippingClassId,
"reviews_allowed": reviewsAllowed,
"average_rating": averageRating,
"rating_count": ratingCount,
"upsell_ids": List<dynamic>.from(upsellIds.map((x) => x)),
"cross_sell_ids": List<dynamic>.from(crossSellIds.map((x) => x)),
"parent_id": parentId,
"purchase_note": purchaseNote,
"categories": List<dynamic>.from(categories.map((x) => x.toJson())),
"tags": List<dynamic>.from(tags.map((x) => x)),
"images": List<dynamic>.from(images.map((x) => x.toJson())),
"attributes": List<dynamic>.from(attributes.map((x) => x)),
"default_attributes": List<dynamic>.from(defaultAttributes.map((x) => x)),
"variations": List<dynamic>.from(variations.map((x) => x)),
"grouped_products": List<dynamic>.from(groupedProducts.map((x) => x)),
"menu_order": menuOrder,
"price_html": priceHtml,
"related_ids": List<dynamic>.from(relatedIds.map((x) => x)),
"meta_data": List<dynamic>.from(metaData.map((x) => x)),
"stock_status": stockStatus,
"_links": links.toJson(),
};
}
class Category {
Category({
required this.id,
required this.name,
required this.slug,
});
int id;
String name;
String slug;
factory Category.fromJson(Map<String, dynamic> json) => Category(
id: json["id"],
name: json["name"],
slug: json["slug"],
);
Map<String, dynamic> toJson() => {
"id": id,
"name": name,
"slug": slug,
};
}
class Dimensions {
Dimensions({
required this.length,
required this.width,
required this.height,
});
String length;
String width;
String height;
factory Dimensions.fromJson(Map<String, dynamic> json) => Dimensions(
length: json["length"],
width: json["width"],
height: json["height"],
);
Map<String, dynamic> toJson() => {
"length": length,
"width": width,
"height": height,
};
}
class Image {
Image({
required this.id,
required this.dateCreated,
required this.dateCreatedGmt,
required this.dateModified,
required this.dateModifiedGmt,
required this.src,
required this.name,
required this.alt,
});
int id;
DateTime dateCreated;
DateTime dateCreatedGmt;
DateTime dateModified;
DateTime dateModifiedGmt;
String src;
String name;
String alt;
factory Image.fromJson(Map<String, dynamic> json) => Image(
id: json["id"],
dateCreated: DateTime.parse(json["date_created"]),
dateCreatedGmt: DateTime.parse(json["date_created_gmt"]),
dateModified: DateTime.parse(json["date_modified"]),
dateModifiedGmt: DateTime.parse(json["date_modified_gmt"]),
src: json["src"],
name: json["name"],
alt: json["alt"],
);
Map<String, dynamic> toJson() => {
"id": id,
"date_created": dateCreated.toIso8601String(),
"date_created_gmt": dateCreatedGmt.toIso8601String(),
"date_modified": dateModified.toIso8601String(),
"date_modified_gmt": dateModifiedGmt.toIso8601String(),
"src": src,
"name": name,
"alt": alt,
};
}
class Links {
Links({
required this.self,
required this.collection,
});
List<Collection> self;
List<Collection> collection;
factory Links.fromJson(Map<String, dynamic> json) => Links(
self: List<Collection>.from(json["self"].map((x) => Collection.fromJson(x))),
collection: List<Collection>.from(json["collection"].map((x) => Collection.fromJson(x))),
);
Map<String, dynamic> toJson() => {
"self": List<dynamic>.from(self.map((x) => x.toJson())),
"collection": List<dynamic>.from(collection.map((x) => x.toJson())),
};
}
class Collection {
Collection({
required this.href,
});
String href;
factory Collection.fromJson(Map<String, dynamic> json) => Collection(
href: json["href"],
);
Map<String, dynamic> toJson() => {
"href": href,
};
}
我正在尝试从 api 中获取一些数据并将其显示在列表中，以便用户可以看到它。
错误信息很清楚。只需使用列表文字：
var productList = <Product>[].obs;
我收到一个关于模型列表的空安全问题
The default 'List' constructor isn't available when null safety is enabled.Try using a list literal, 'List.filled' or 'List.generate'.
这是代码：
var productList = List<Product>().obs;
模态代码：
import 'dart:convert';
List<Product> welcomeFromJson(String str) => List<Product>.from(json.decode(str).map((x) => Product.fromJson(x)));
String welcomeToJson(List<Product> data) => json.encode(List<dynamic>.from(data.map((x) => x.toJson())));
class Product {
Product({
required this.id,
required this.name,
required this.slug,
required this.permalink,
required this.dateCreated,
required this.dateCreatedGmt,
required this.dateModified,
required this.dateModifiedGmt,
required this.type,
required this.status,
required this.featured,
required this.catalogVisibility,
required this.description,
required this.shortDescription,
required this.sku,
required this.price,
required this.regularPrice,
required this.salePrice,
this.dateOnSaleFrom,
this.dateOnSaleFromGmt,
this.dateOnSaleTo,
this.dateOnSaleToGmt,
required this.onSale,
required this.purchasable,
required this.totalSales,
required this.virtual,
required this.downloadable,
required this.downloads,
required this.downloadLimit,
required this.downloadExpiry,
required this.externalUrl,
required this.buttonText,
required this.taxStatus,
required this.taxClass,
required this.manageStock,
required this.stockQuantity,
required this.backorders,
required this.backordersAllowed,
required this.backordered,
required this.lowStockAmount,
required this.soldIndividually,
required this.weight,
required this.dimensions,
required this.shippingRequired,
required this.shippingTaxable,
required this.shippingClass,
required this.shippingClassId,
required this.reviewsAllowed,
required this.averageRating,
required this.ratingCount,
required this.upsellIds,
required this.crossSellIds,
required this.parentId,
required this.purchaseNote,
required this.categories,
required this.tags,
required this.images,
required this.attributes,
required this.defaultAttributes,
required this.variations,
required this.groupedProducts,
required this.menuOrder,
required this.priceHtml,
required this.relatedIds,
required this.metaData,
required this.stockStatus,
required this.links,
});
int id;
String name;
String slug;
String permalink;
DateTime dateCreated;
DateTime dateCreatedGmt;
DateTime dateModified;
DateTime dateModifiedGmt;
String type;
String status;
bool featured;
String catalogVisibility;
String description;
String shortDescription;
String sku;
String price;
String regularPrice;
String salePrice;
dynamic dateOnSaleFrom;
dynamic dateOnSaleFromGmt;
dynamic dateOnSaleTo;
dynamic dateOnSaleToGmt;
bool onSale;
bool purchasable;
int totalSales;
bool virtual;
bool downloadable;
List<dynamic> downloads;
int downloadLimit;
int downloadExpiry;
String externalUrl;
String buttonText;
String taxStatus;
String taxClass;
bool manageStock;
dynamic stockQuantity;
String backorders;
bool backordersAllowed;
bool backordered;
dynamic lowStockAmount;
bool soldIndividually;
String weight;
Dimensions dimensions;
bool shippingRequired;
bool shippingTaxable;
String shippingClass;
int shippingClassId;
bool reviewsAllowed;
String averageRating;
int ratingCount;
List<dynamic> upsellIds;
List<dynamic> crossSellIds;
int parentId;
String purchaseNote;
List<Category> categories;
List<dynamic> tags;
List<Image> images;
List<dynamic> attributes;
List<dynamic> defaultAttributes;
List<dynamic> variations;
List<dynamic> groupedProducts;
int menuOrder;
String priceHtml;
List<int> relatedIds;
List<dynamic> metaData;
String stockStatus;
Links links;
factory Product.fromJson(Map<String, dynamic> json) => Product(
id: json["id"],
name: json["name"],
slug: json["slug"],
permalink: json["permalink"],
dateCreated: DateTime.parse(json["date_created"]),
dateCreatedGmt: DateTime.parse(json["date_created_gmt"]),
dateModified: DateTime.parse(json["date_modified"]),
dateModifiedGmt: DateTime.parse(json["date_modified_gmt"]),
type: json["type"],
status: json["status"],
featured: json["featured"],
catalogVisibility: json["catalog_visibility"],
description: json["description"],
shortDescription: json["short_description"],
sku: json["sku"],
price: json["price"],
regularPrice: json["regular_price"],
salePrice: json["sale_price"],
dateOnSaleFrom: json["date_on_sale_from"],
dateOnSaleFromGmt: json["date_on_sale_from_gmt"],
dateOnSaleTo: json["date_on_sale_to"],
dateOnSaleToGmt: json["date_on_sale_to_gmt"],
onSale: json["on_sale"],
purchasable: json["purchasable"],
totalSales: json["total_sales"],
virtual: json["virtual"],
downloadable: json["downloadable"],
downloads: List<dynamic>.from(json["downloads"].map((x) => x)),
downloadLimit: json["download_limit"],
downloadExpiry: json["download_expiry"],
externalUrl: json["external_url"],
buttonText: json["button_text"],
taxStatus: json["tax_status"],
taxClass: json["tax_class"],
manageStock: json["manage_stock"],
stockQuantity: json["stock_quantity"],
backorders: json["backorders"],
backordersAllowed: json["backorders_allowed"],
backordered: json["backordered"],
lowStockAmount: json["low_stock_amount"],
soldIndividually: json["sold_individually"],
weight: json["weight"],
dimensions: Dimensions.fromJson(json["dimensions"]),
shippingRequired: json["shipping_required"],
shippingTaxable: json["shipping_taxable"],
shippingClass: json["shipping_class"],
shippingClassId: json["shipping_class_id"],
reviewsAllowed: json["reviews_allowed"],
averageRating: json["average_rating"],
ratingCount: json["rating_count"],
upsellIds: List<dynamic>.from(json["upsell_ids"].map((x) => x)),
crossSellIds: List<dynamic>.from(json["cross_sell_ids"].map((x) => x)),
parentId: json["parent_id"],
purchaseNote: json["purchase_note"],
categories: List<Category>.from(json["categories"].map((x) => Category.fromJson(x))),
tags: List<dynamic>.from(json["tags"].map((x) => x)),
images: List<Image>.from(json["images"].map((x) => Image.fromJson(x))),
attributes: List<dynamic>.from(json["attributes"].map((x) => x)),
defaultAttributes: List<dynamic>.from(json["default_attributes"].map((x) => x)),
variations: List<dynamic>.from(json["variations"].map((x) => x)),
groupedProducts: List<dynamic>.from(json["grouped_products"].map((x) => x)),
menuOrder: json["menu_order"],
priceHtml: json["price_html"],
relatedIds: List<int>.from(json["related_ids"].map((x) => x)),
metaData: List<dynamic>.from(json["meta_data"].map((x) => x)),
stockStatus: json["stock_status"],
links: Links.fromJson(json["_links"]),
);
Map<String, dynamic> toJson() => {
"id": id,
"name": name,
"slug": slug,
"permalink": permalink,
"date_created": dateCreated.toIso8601String(),
"date_created_gmt": dateCreatedGmt.toIso8601String(),
"date_modified": dateModified.toIso8601String(),
"date_modified_gmt": dateModifiedGmt.toIso8601String(),
"type": type,
"status": status,
"featured": featured,
"catalog_visibility": catalogVisibility,
"description": description,
"short_description": shortDescription,
"sku": sku,
"price": price,
"regular_price": regularPrice,
"sale_price": salePrice,
"date_on_sale_from": dateOnSaleFrom,
"date_on_sale_from_gmt": dateOnSaleFromGmt,
"date_on_sale_to": dateOnSaleTo,
"date_on_sale_to_gmt": dateOnSaleToGmt,
"on_sale": onSale,
"purchasable": purchasable,
"total_sales": totalSales,
"virtual": virtual,
"downloadable": downloadable,
"downloads": List<dynamic>.from(downloads.map((x) => x)),
"download_limit": downloadLimit,
"download_expiry": downloadExpiry,
"external_url": externalUrl,
"button_text": buttonText,
"tax_status": taxStatus,
"tax_class": taxClass,
"manage_stock": manageStock,
"stock_quantity": stockQuantity,
"backorders": backorders,
"backorders_allowed": backordersAllowed,
"backordered": backordered,
"low_stock_amount": lowStockAmount,
"sold_individually": soldIndividually,
"weight": weight,
"dimensions": dimensions.toJson(),
"shipping_required": shippingRequired,
"shipping_taxable": shippingTaxable,
"shipping_class": shippingClass,
"shipping_class_id": shippingClassId,
"reviews_allowed": reviewsAllowed,
"average_rating": averageRating,
"rating_count": ratingCount,
"upsell_ids": List<dynamic>.from(upsellIds.map((x) => x)),
"cross_sell_ids": List<dynamic>.from(crossSellIds.map((x) => x)),
"parent_id": parentId,
"purchase_note": purchaseNote,
"categories": List<dynamic>.from(categories.map((x) => x.toJson())),
"tags": List<dynamic>.from(tags.map((x) => x)),
"images": List<dynamic>.from(images.map((x) => x.toJson())),
"attributes": List<dynamic>.from(attributes.map((x) => x)),
"default_attributes": List<dynamic>.from(defaultAttributes.map((x) => x)),
"variations": List<dynamic>.from(variations.map((x) => x)),
"grouped_products": List<dynamic>.from(groupedProducts.map((x) => x)),
"menu_order": menuOrder,
"price_html": priceHtml,
"related_ids": List<dynamic>.from(relatedIds.map((x) => x)),
"meta_data": List<dynamic>.from(metaData.map((x) => x)),
"stock_status": stockStatus,
"_links": links.toJson(),
};
}
class Category {
Category({
required this.id,
required this.name,
required this.slug,
});
int id;
String name;
String slug;
factory Category.fromJson(Map<String, dynamic> json) => Category(
id: json["id"],
name: json["name"],
slug: json["slug"],
);
Map<String, dynamic> toJson() => {
"id": id,
"name": name,
"slug": slug,
};
}
class Dimensions {
Dimensions({
required this.length,
required this.width,
required this.height,
});
String length;
String width;
String height;
factory Dimensions.fromJson(Map<String, dynamic> json) => Dimensions(
length: json["length"],
width: json["width"],
height: json["height"],
);
Map<String, dynamic> toJson() => {
"length": length,
"width": width,
"height": height,
};
}
class Image {
Image({
required this.id,
required this.dateCreated,
required this.dateCreatedGmt,
required this.dateModified,
required this.dateModifiedGmt,
required this.src,
required this.name,
required this.alt,
});
int id;
DateTime dateCreated;
DateTime dateCreatedGmt;
DateTime dateModified;
DateTime dateModifiedGmt;
String src;
String name;
String alt;
factory Image.fromJson(Map<String, dynamic> json) => Image(
id: json["id"],
dateCreated: DateTime.parse(json["date_created"]),
dateCreatedGmt: DateTime.parse(json["date_created_gmt"]),
dateModified: DateTime.parse(json["date_modified"]),
dateModifiedGmt: DateTime.parse(json["date_modified_gmt"]),
src: json["src"],
name: json["name"],
alt: json["alt"],
);
Map<String, dynamic> toJson() => {
"id": id,
"date_created": dateCreated.toIso8601String(),
"date_created_gmt": dateCreatedGmt.toIso8601String(),
"date_modified": dateModified.toIso8601String(),
"date_modified_gmt": dateModifiedGmt.toIso8601String(),
"src": src,
"name": name,
"alt": alt,
};
}
class Links {
Links({
required this.self,
required this.collection,
});
List<Collection> self;
List<Collection> collection;
factory Links.fromJson(Map<String, dynamic> json) => Links(
self: List<Collection>.from(json["self"].map((x) => Collection.fromJson(x))),
collection: List<Collection>.from(json["collection"].map((x) => Collection.fromJson(x))),
);
Map<String, dynamic> toJson() => {
"self": List<dynamic>.from(self.map((x) => x.toJson())),
"collection": List<dynamic>.from(collection.map((x) => x.toJson())),
};
}
class Collection {
Collection({
required this.href,
});
String href;
factory Collection.fromJson(Map<String, dynamic> json) => Collection(
href: json["href"],
);
Map<String, dynamic> toJson() => {
"href": href,
};
}
我正在尝试从 api 中获取一些数据并将其显示在列表中，以便用户可以看到它。
错误信息很清楚。只需使用列表文字：
var productList = <Product>[].obs;